Transcatheter Heart Valve Delivery System With Reduced Area Moment of Inertia

ABSTRACT

A device for percutaneously repairing a heart valve of a patient including a self-expanding, stented prosthetic heart valve and a delivery system. The delivery system includes delivery sheath slidably receiving an inner shaft forming a coupling structure. A capsule of the delivery sheath includes a distal segment and a proximal segment. An outer diameter of the distal segment is greater than that of the proximal segment. An area moment of inertia of the distal segment can be greater than an area moment of inertia of the proximal segment. Regardless, an axial length of the distal segment is less than the axial length of the prosthesis. In a loaded state, the prosthesis engages the coupling structure and is compressively retained within the capsule. The capsule is unlikely to kink when traversing the patient&#39;s vasculature, such as when tracking around the aortic arch, promoting recapturing of the prosthesis.

BACKGROUND

The present disclosure relates to systems and methods for percutaneousimplantation of a heart valve prosthesis. More particular, it relates todelivery systems and methods for transcatheter implantation of aself-expanding, stented prosthetic heart valve.

Diseased or otherwise deficient heart valves can be repaired or replacedwith an implanted prosthetic heart valve. Conventionally, heart valvereplacement surgery is an open-heart procedure conducted under generalanesthesia, during which the heart is stopped and blood flow iscontrolled by a heart-lung bypass machine. Traditional open surgeryinflicts significant patient trauma and discomfort, and exposes thepatient to a number of potential risks, such as infection, stroke, renalfailure, and adverse effects associated with the use of the heart-lungbypass machine, for example.

Due to the drawbacks of open-heart surgical procedures, there has beenan increased interest in minimally invasive and percutaneous replacementof cardiac valves. With these percutaneous transcatheter (ortransluminal) techniques, a valve prosthesis is compacted for deliveryin a catheter and then advanced, for example, through an opening in thefemoral artery and through the descending aorta to the heart, where theprosthesis is then deployed in the annulus of the valve to be repaired(e.g., the aortic valve annulus). Although transcatheter techniques haveattained widespread acceptance with respect to the delivery ofconventional stents to restore vessel patency, only mixed results havebeen realized with percutaneous delivery of a relatively more complexprosthetic heart valve.

Various types and configurations of prosthetic heart valves areavailable, and continue to be refined. The actual shape andconfiguration of any particular prosthetic heart valve is dependent tosome extent upon native shape and size of the valve being repaired(i.e., mitral valve, tricuspid valve, aortic valve, or pulmonary valve).In general, prosthetic heart valve designs attempt to replicate thefunctions of the valve being replaced and thus will include valveleaflet-like structures. With a bioprosthesis construction, thereplacement valve may include a valved vein segment that is mounted insome manner within an expandable stent frame to make a valved stent (or“stented prosthetic heart valve”). For many percutaneous delivery andimplantation systems, the self-expanding valved stent is crimped down toa desired size and held in that compressed state within an outer sheath,for example. Retracting the sheath from the valved stent allows thestent to self-expand to a larger diameter, such as when the valved stentis in a desired position within a patient. In other percutaneousimplantation systems, the valved stent can be initially provided in anexpanded or uncrimped condition, then crimped or compressed on a balloonportion of catheter until it is as close to the diameter of the catheteras possible. Once delivered to the implantation site, the balloon isinflated to deploy the so-configured prosthesis. With either of thesetypes of percutaneous stent delivery systems, conventional sewing of theprosthetic heart valve to the patient's native tissue is typically notnecessary.

It is imperative that the stented prosthetic heart valve be accuratelylocated relative to the native annulus immediately prior to fulldeployment from the catheter as successful implantation requires thetranscatheter prosthetic heart valve intimately lodge and seal againstthe native annulus. If the prosthesis is incorrectly positioned relativeto the native annulus, serious complications can result as the deployeddevice can leak and may even dislodge from the implantation site. As apoint of reference, this same concern does not arise in the context ofother vascular stents; with these procedures, if the target site is“missed,” another stent is simply deployed to “make-up” the difference.

While imaging technology can be employed as part of the implantationprocedure to assist a clinician in better evaluating a location of thetranscatheter prosthetic heart valve immediately prior to fulldeployment, in many instances this evaluation alone is insufficient.Instead, clinicians desire the ability to partially deploy theprosthesis, evaluate a position relative to the native annulus, andreposition the prosthesis prior to full deployment if deemed necessary.Repositioning, in turn, requires the prosthesis first be re-compressedand re-located back within the outer delivery sheath. Stated otherwise,the partially deployed, stented prosthetic heart valve must be“recaptured” by the delivery system, and in particular within the outersheath. While, in theory, the recapturing of a partially deployedstented prosthetic heart valve is straight forward, in actual practice,the constraints presented by the implantation access path and thestented prosthetic heart valve itself render the procedure exceedinglydifficult.

For example, the stented prosthetic heart valve is purposefully designto rigidly resist collapsing forces once deployed. With a self-expandingstented prosthetic heart valve, then, the stent frame must generate ahigh radial force when expanding from the compressed state to properlyanchor itself in the anatomy of the heart. The corresponding deliverysheath segment (or capsule) compressively retaining the stented valveduring delivery to the implantation site is radially stiffened tosufficiently resist radial expansion, and conventionally encompasses orsurrounds an entire length of the prosthesis (i.e., while the relativelyrigid capsule can be proximally coupled to a more compliant cathetershaft, the capsule itself surrounds an entirety of the prosthesis).Further, to facilitate compressed loading of the self-expanding stentframe into the outer sheath, the capsule typically has an increasedinner (and outer) diameter as compared to the other, more proximalsegments of the outer sheath. As part of most transcatheter heart valvereplacement procedures, the delivery system (e.g., a prosthetic heartvalve compressively retained within an outer sheath) must traverse theaortic arch (e.g., in a retrograde approach). While the relativelyrigid, relatively large delivery sheath capsules are viable foraccessing the native heart valve via the aortic arch (or other tortuousvasculature), the so-configured delivery sheath may undesirably buckleor “kink”, especially when traversing the various curvatures of theaortic arch. Once kinked, it is virtually impossible for the deliverysheath capsule to be advanced over a partially-deployed prosthesis as isotherwise necessary for recapture. Simply stated, due to the relativelylong stiff section of the conventional delivery sheath, successfuldelivery of a prosthetic heart valve through the tortuous vasculature,such as required for retrograde delivery of a prosthetic aortic heartvalve, as well as recapturing a partially deployed prosthetic heartvalve, has proven to be difficult.

In light of the above, although there have been advances in percutaneousvalve replacement techniques and devices, there is a continued desire toprovide different delivery systems for delivering cardiac replacementvalves, and in particular self-expanding stented prosthetic heartvalves, to an implantation site in a minimally invasive and percutaneousmanner that satisfies the constraints associated with heart valveimplantation (e.g., traversing the aortic arch).

SUMMARY

Some aspects in accordance with principles of the present disclosurerelate to a device for repairing a heart valve of a patient. The deviceincludes a prosthetic heart valve and a delivery system. The prostheticheart valve has a stent frame and a valve structure. The valve structureis attached to the stent frame and forms at least two valve leaflets.Further, the prosthetic heart valve is radially self-expandable from acompressed arrangement to a natural arrangement, with the stent framedefining an axial length. The delivery system includes an inner shaftassembly and a delivery sheath. The inner shaft assembly includes anintermediate portion forming a coupling structure. The delivery sheathassembly defines a lumen sized to slidably receive the inner shaftassembly, and includes a shaft and a capsule. The capsule extendsdistally from the shaft and includes a distal segment and a proximalsegment. An outer diameter of the capsule distal segment is greater thanan outer diameter of the capsule proximal segment. Further, an axiallength of the distal segment is less than the axial length of the stentframe. With this in mind, the device is configured to provide a loadedstate in which the prosthetic heart valve engages the coupling structureand is compressively retained in the compressed arrangement within thecapsule. In some embodiments, an inner diameter of the capsule distalsegment is greater than an inner diameter of the capsule proximalsegment. In other embodiments, a radial stiffness of the capsule distalsegment is greater than a radial stiffness of the capsule proximalsegment. In yet other embodiments, an area moment of inertia of thedistal segment is greater than area moment of inertia of the proximalsegment. In yet other embodiments, in the loaded state, an inflow sideof the prosthetic heart valve is crimped within the distal segment ofthe capsule, and an outflow side of the prosthetic heart valve iscrimped within the proximal segment. With these and other constructions,the capsule provides requisite resistance to radial expansion of theprosthetic heart valve, yet exhibits sufficient conformability fortraversing the tortuous vasculature of the patient, for example thevarious curvatures of the aortic arch. For example, by providing thecapsule with a lower area moment of inertia (as compared to the outersheath capsule of a conventional self-expanding stented prosthetic heartvalve delivery system), the devices of the present disclosure greatlyreduce the likelihood of the capsule becoming kinked when trackingaround the aortic arch. This feature, in turn, facilitates easierrecapturing of the prosthetic heart valve with the capsule if desired.

Yet other aspects in accordance with principles of the presentdisclosure relate to a method of loading a transcatheter delivery systemwith a prosthetic heart valve. The prosthetic heart valve has a valvestructure attached to a stent frame, and is radially self-expandablefrom a compressed arrangement to a natural arrangement. The methodincludes receiving a delivery system including an inner shaft assemblyand a delivery sheath assembly. The inner shaft assembly includes anintermediate portion forming a coupling structure. The delivery sheathassembly defines a lumen sized to slidably receive the inner shaftassembly, and includes a capsule extending distally from a shaft. Thecapsule provides a distal segment and a proximal segment, with an outerdiameter of the distal segment being greater than an outer diameter ofthe proximal segment. The prosthetic heart valve is disposed over theinner shaft assembly such that a proximal region of the prosthetic heartvalve is adjacent the coupling structure. The prosthetic heart valve iscompressed to the compressed arrangement over the inner shaft assemblyby locating the capsule over the prosthetic heart valve and crimping theprosthetic heart valve into engagement with the coupling structure. Inthis loaded state, the distal segment of the capsule encompasses adistal region of the prosthetic heart valve, and a proximal region ofthe prosthetic heart valve is encompassed by the capsule proximalsegment. In some embodiments, the method of loading the transcatheterdelivery system includes the distal segment of the capsule encompassingan entirety of the valve structure of the prosthetic heart valve, andless than entirety of the corresponding stent frame.

Yet other aspects in accordance with principles of the presentdisclosure relate to a method of repairing a defective heart valve of apatient. The method includes receiving a delivery system loaded with aradially self-expanding prosthetic heart valve having a valve structureattached to a stent frame. The delivery system includes an inner shaftassembly slidably received within a delivery sheath assembly. Thedelivery sheath assembly provides a capsule forming a distal segment anda proximal segment, with an outer diameter of the distal segment beinggreater than that of the proximal segment. In this regard, the distalsegment of the capsule is disposed over and compressively retains adistal region of the prosthetic heart valve, whereas the capsuleproximal segment is disposed over and compressively retains a proximalregion of the prosthetic heart valve such that the capsule retains theprosthetic heart valve over the inner shaft assembly in a compressedarrangement. The prosthetic heart valve is inserted into a bodily lumenwhile constrained within the capsule. The delivery system is manipulatedto guide the prosthetic heart valve, in the compressed arrangement,through the patient's vasculature and into the defective heart valve.Finally, the capsule is withdrawn from the prosthetic heart valve topermit the prosthetic heart valve to self-expand and release from thedelivery system and into engagement with the native heart valve. In someembodiments, the method includes manipulating the prosthetic heart valvearound the patient's aortic arch, with the capsule not kinking whentravelling across the aortic arch. In yet other embodiments, the methodincludes partially deploying the prosthetic heart valve from thecapsule, and then recapturing the prosthetic heart valve within thecapsule.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side view of a stented prosthetic heart valve in a natural,expanded arrangement and useful with systems and methods of the presentdisclosure;

FIG. 1B is a side view of the prosthesis of FIG. 1A in a compressedarrangement;

FIG. 2 is a perspective view of a delivery system in accordance withprinciples of the present disclosure and useful for percutaneouslydelivering the prosthetic heart valve of FIGS. 1A and 1B to a heartvalve implantation site;

FIG. 3 is a perspective, exploded view of the delivery system of FIG. 2;

FIG. 4 is an enlarged, cross-sectional view of a portion of a deliverysheath assembly component of the delivery system of FIG. 2;

FIG. 5A is a cross-sectional view of the delivery sheath portion of FIG.4 along side the prosthetic heart valve of FIG. 1B;

FIG. 5B is a simplified, cross-sectional view of the delivery sheathportion and prosthetic heart valve of FIG. 5A when assembled to a loadedstate;

FIG. 6A is a simplified side view of the delivery system of FIG. 2loaded with the prosthetic heart valve of FIG. 1A to define a heartvalve repair device in accordance with principles of the presentdisclosure;

FIG. 6B is a cross-sectional view of the device of FIG. 6A;

FIG. 6C is a simplified, cross-sectional view of a prior transcatheterprosthetic heart valve delivery system loaded with a prosthetic heartvalve;

FIG. 7 is a simplified cross-sectional view of the device of FIG. 6A ina partially deployed state; and

FIGS. 8A and 8B illustrate use of the device of FIG. 6A inpercutaneously delivering the prosthetic heart valve to an aortic valveimplantation site via an aortic arch of the patient.

DETAILED DESCRIPTION

As referred to herein, the prosthetic heart valve as used in accordancewith the various devices and methods may include a wide variety ofdifferent configurations, such as a bioprosthetic heart valve havingtissue leaflets or a synthetic heart valve having a polymeric, metallic,or tissue-engineered leaflets, and can be specifically configured forreplacing any heart valve. Thus, the prosthetic heart valve useful withthe devices and methods of the present disclosure can be generally usedfor replacement of a native aortic, mitral, pulmonic, or tricuspidvalves, for use as a venous valve, or to replace a failed bioprosthesis,such as in the area of an aortic valve or mitral valve, for example.

In general terms, the prosthetic heart valves of the present disclosureinclude a stent or stent frame maintaining a valve structure (tissue orsynthetic), with the stent having a normal, expanded arrangement orstate and collapsible to a compressed arrangement for loading within thedelivery system. The stent is normally constructed to self-deploy orself-expand when released from the delivery system. For example, thestented prosthetic heart valve useful with the present disclosure can bea prosthetic valve sold under the trade name CoreValve® available fromMedtronic CoreValve, LLC. Other non-limiting examples of transcatheterheart valve prostheses useful with systems and methods of the presentdisclosure are described in U.S. Publication Nos. 2006/0265056;2007/0239266; and 2007/0239269, the teachings of each of which areincorporated herein by reference. The stents or stent frames are supportstructures that comprise a number of struts or wire portions arrangedrelative to each other to provide a desired compressibility and strengthto the prosthetic heart valve. In general terms, the stents or stentframes of the present disclosure are generally tubular supportstructures having an internal area in which valve structure leafletswill be secured. The leaflets can be formed from a verity of materials,such as autologous tissue, xenograph material, or synthetics as areknown in the art. The leaflets may be provided as a homogenous,biological valve structure, such as porcine, bovine, or equine valves.Alternatively, the leaflets can be provided independent of one another(e.g., bovine or equine paracardial leaflets) and subsequently assembledto the support structure of the stent frame. In another alternative, thestent frame and leaflets can be fabricated at the same time, such as maybe accomplished using high-strength nano-manufactured NiTi filmsproduced at Advance BioProsthetic Surfaces (ABPS), for example. Thestent frame support structures are generally configured to accommodateat least two, alternatively three, leaflets; however, replacementprosthetic heart valve of the types described herein can incorporatemore or less than three leaflets.

Some embodiments of the stent frames can be a series of wires or wiresegments arranged such that they are capable of self-transitioning froma collapsed arrangement to a normal, radially expanded arrangement. Inconstructions, a number of individual wires comprising the stent framesupport structure can be formed of a metal or other material. Thesewires are arranged in such a way that the stent frame support structureallows for folding or compressing or crimping to the compressedarrangement in which its internal diameter is smaller than its internaldiameter when in the natural, expanded arrangement. In the collapsedarrangement, such a stent frame support structure with attached valvescan be mounted onto a delivery system. The stent frame supportstructures are configured so that they can be changed to their natural,expanded arrangement when desired, such as by the relative movement ofone or more sheaths relative to a length of the stent frame.

The wires of the stent frame support structures in embodiments of thepresent disclosure can be formed from a shape memory material such as anickel titanium alloy (e.g., Nitinol™). With this material, the supportstructure is self-expandable from the compressed arrangement to thenatural, expanded arrangement, such as by the application of heat,energy, and the like, or by the removal of external forces (e.g.,compressive forces). This stent frame support structure can also becompressed and re-expanded multiple times without damaging the structureof the stent frame. In addition, the stent frame support structure ofsuch an embodiment may be laser-cut from a single piece of material ormay be assembled from a number of different components. For these typesof stent frame structures, one example of a delivery system that can beused includes a catheter with a retractable sheath that covers the stentframe until it is to be deployed, at which point the sheath can beretracted to allow the stent frame to self-expand. Further details ofsuch embodiments are discussed below.

With the above understanding in mind, one non-limiting example of astented prosthetic heart valve 20 useful with devices and methods of thepresent disclosure is illustrated in FIG. 1A. As a point of reference,the prosthetic heart valve 20 is shown in a natural or expandedarrangement in the view of FIG. 1A; FIG. 1B illustrates the prostheticheart valve 20 in a compressed arrangement (e.g., when compressivelyretained within an outer tube or sheath). The prosthetic heart valve 20includes a stent or stent frame 22 and a valve structure 24. The stentframe 22 can assume any of the forms described above, and is generallyconstructed so as to be self-expandable from the compressed arrangement(FIG. 1B) to the natural, expanded arrangement (FIG. 1A). The valvestructure 24 is assembled to the stent frame 22 and forms or providestwo or more (typically three) leaflets 26 a, 26 b. The valve structure24 can assume any of the forms described above, and can be assembled tothe stent frame 22 in various manners, such as by sewing the valvestructure 24 to one or more of the wire segments 28 defined by the stentframe 22.

With the but one acceptable construction of FIGS. 1A and 1B, theprosthetic heart valve 20 is configured for repairing an aortic valve.Alternatively, other shapes are also envisioned to adapt to the specificanatomy of the valve to be repaired (e.g., stented prosthetic heartvalves in accordance with the present disclosure can be shaped and/orsized for replacing a native mitral, pulmonic, or tricuspid valve).Regardless, the stent frame 22 defines an axial length L_(P) of theprosthetic heart valve 20. With the one construction of FIGS. 1A and 1B,the valve structure 24 extends less than the entire length L_(P) of thestent frame 22. In particular, the valve structure 24 is assembled to,and extends along, an inflow region 30 of the prosthetic heart valve 20,whereas an outflow region 32 is free of the valve structure 24 material.As a point of reference, “inflow” and “outflow” terminology is inreference to an arrangement of the prosthetic heart valve 20 upon finalimplantation relative to the native aortic valve (or other valve) beingrepaired. A wide variety of constructions are also acceptable and withinthe scope of the present disclosure. For example, in other embodiments,the valve structure 24 can extend along an entirety, or a near entirety,of a length of the stent frame 22.

With the above understanding of the prosthetic heart valve 20 in mind,one embodiment of a delivery system 40 in accordance with the presentdisclosure is shown in FIG. 2. As a point of reference, although thedelivery system 40 can be loaded with a stented prosthetic heart valvefor percutaneous delivery thereof, such a prosthesis is not visible inthe view of FIG. 2. The delivery system 40 includes a delivery sheathassembly 42, an inner shaft assembly 44 (referenced generally), a handle46, and an optional outer stability tube 48. Details on the variouscomponents are provided below. In general terms, however, the deliverysystem 40 is transitionable from a loaded state (shown in FIG. 2) inwhich the stented prosthetic heart valve is contained within a capsule50 of the delivery sheath assembly 42, to a deployed state in which thecapsule 50 is retracted from the prosthetic heart valve, therebypermitting the prosthetic heart valve to self-expand (or alternativelybe caused to expand by a separate mechanism such as a balloon) andrelease from the delivery system 40. In this regard, an actuatormechanism (described below) can be provided with the handle 46 thatfacilitates transitioning from the loaded state to the deployed state,operating to proximally retract the delivery sheath assembly 42, and inparticular the capsule 50, from over the prosthetic heart valve. Thedelivery system 40 can be used with a conventional introducer device(not shown), with the optional outer stability tube 48, where provided,serving to frictionally isolate the delivery sheath assembly 42 from theintroducer device.

Representative configurations of the components 42-48 in accordance withsome embodiments of delivery systems encompassed by the presentdisclosure are shown in greater detail in FIG. 3. In this regard,various features illustrated in FIG. 3 can be modified or replaced withdiffering structures and/or mechanisms. Thus, the present disclosure isin no way limited to the inner shaft assembly 44, the handle 46, etc.,as shown and described below. In more general terms, then, deliverysystems in accordance with principles of the present disclosure providefeatures capable of compressively retaining a self-expanding, stentedprosthetic heart valve (e.g., the delivery sheath capsule 50), alongwith one or more mechanisms capable of effectuating release ordeployment of the heart valve prosthesis from the delivery system.

The delivery sheath assembly 42 includes the capsule 50 and a shaft 52,and defines a lumen 54 (referenced generally) extending from a distalend 56 to a proximal end 58. The capsule 50 is attached to, and extendsdistally from, the shaft 52.

The capsule 50 is constructed to compressively retain theself-expanding, stented prosthetic heart valve, and includes or definesa distal segment 60 and a proximal segment 62. The distal segment 60 canterminate at the distal end 56 of the delivery sheath assembly 52; inother embodiments, an additional tubular structure is provided distalthe distal segment 60 (e.g., polymer tubing carrying a radiopaquemarker) that is not intended or constructed to compressively retain theprosthetic heart valve 20 (FIG. 1B) in the loaded state, and thus is notpart of the capsule 50. With additional reference to FIG. 4, theproximal segment 62 can be formed as a continuation of the shaft 52.Alternatively, the proximal segment 62 and the shaft 52 can havediffering constructions. Regardless, construction of the distal segment60 differs from that of the proximal segment 62 so as to generate aconnection point or intermediate zone 64 between the segments 60, 62.Further, an axial length L_(D) of at least the distal segment 60selected in accordance with the axial length L_(P) (FIGS. 1A and 1B) ofthe prosthetic heart valve 20 to be loaded within the system 40 asdescribed below.

The differing constructions of the distal and proximal segment 60, 62can assume various forms. For example, in some constructions, an outerdiameter of the distal segment 60 is greater than an outer diameter ofthe proximal segment 62. Further, an inner diameter of the distalsegment 60 can be greater than an inner diameter of the proximal segment62. Alternatively or in addition, a radial stiffness of the distalsegment 60 can be greater than a radial stiffness of the proximalsegment 62. Even further, an area moment of inertia of the distalsegment 60 can be greater than an area moment of inertia of the proximalsegment 62. As a point of reference, the area moment of inertia of thecapsule segments 60, 62 (also known as second moment of inertia) is aproperty of the shape of the capsule segment 60, 62, and can be used topredict the deflection and conformability to the shape of the tortuousvasculature through which the capsule 50 is directed. One suchvasculature region is the aortic arch; the conformability of the capsule50 to the aortic arch depends on the geometry of the cross-section ofthe capsule segment 60, 62. Lowering the area moment of inertia of thecapsule 50 as a whole (e.g., configuring the proximal segment 62 with alower area moment of inertia than the distal segment 60 results in thecapsule 50 collectively having a reduced area moment of inertia ascompared to a conventional, entirely uniform capsule construction) willlessen the likelihood that the capsule 50 will kink when advancedthrough the aortic arch.

In some embodiments, the distal segment 60 is a cut metal tube (e.g., alaser-cut hypotube) embedded or encapsulated within a polymer (e.g.,Pebax®), whereas the proximal segment 62 is a braided polymer tube. Avariety of other constructions are also acceptable so long as the distalsegment 60 has one or more of a greater outer diameter, inner diameter,area moment of inertia, or stiffness as compared to the proximal segment62, and the capsule segments 60, 62 each exhibit sufficient radial orcircumferential rigidity so as to overtly resist the expected expansiveforces associated with the corresponding region of the stentedprosthetic heart valve to be compressively held within the capsule 50.Thus, for example, the distal and proximal segment 60, 62 can be formedof a similar material (e.g., a polymer tube, braided tube, etc.). Otheracceptable constructions of the capsule 50 include high strengthpolymeric materials (e.g., polyamide, PEEK, etc.).

FIG. 5A illustrates a relationship between the axial length L_(D) of thecapsule distal segment 60 and the axial length L_(P) of the prostheticheart valve 20. In particular, the capsule distal segment axial lengthL_(D) is less than the prosthetic heart valve axial length L. As a pointof clarification, with embodiments in which the proximal segment 62 isformed or defined as a homogenous continuation of the delivery sheathshaft 52, a perceptible demarcation between the proximal segment 62 andthe shaft 52 will not exist. When loaded with the prosthetic heat valve20, however, a portion of the shaft 52 will reside over a region of theprosthetic heart valve 20 and can be viewed as defining the proximalsegment 62 of the capsule 50. As best shown in FIG. 5B, upon loading ofthe prosthetic heart valve 20 (in the compressed arrangement) within thecapsule 50, the distal segment 60 extends over or encompasses less thanan entirety of the prosthetic heart valve 20, for example less than anentirety of the stent frame 22. In some constructions, the capsuledistal segment axial length L_(D) is slightly greater than the length ofthe valve structure 24 such that the valve structure 24 is within thedistal segment 60 in the loaded state, with a remainder of the stentframe 22 being within the proximal segment 62. In yet other embodiments,the capsule distal segment axial length L_(D) is selected such that inthe loaded state, the inflow region 30 of the prosthetic heart valve 20is within the distal segment 60, and the outflow region 32 is within theproximal segment 62. Regardless, unlike conventional transcatheterdelivery system configurations in which the stiffer, increased outerdiameter portion of the delivery sheath is sized to encompass anentirety of the prosthetic heart valve when loaded, the stiffer/largerdistal segment 60 associated with the delivery system 40 of the presentdisclosure has a reduced length that is less than a length of theselected prosthetic heart valve 20.

Returning to FIGS. 2 and 3, the shaft 52 extends proximally from thecapsule 50, and can be formed as a braided tube. For example, the shaft52 can be a thermoplastic elastomer, such as Pebax®, with an embeddedbraided metal layer constructed from stainless steel wire. Otherconfigurations are also acceptable, with the shaft 52 serving to connectthe capsule 50 with the handle 46. As described above, and in someconstructions, the proximal segment 62 of the capsule 50 is defined as acontinuation of the shaft 52, with the shaft 52 being coupled to thedistal segment 60 at the connection point 64 (e.g., heat or adhesivebonding). The shaft 52 is constructed to be sufficiently flexible forpassage through a patient's vasculature yet exhibits sufficientlongitudinal rigidity to effectuate desired axial movement of thecapsule 50. In other words, proximal retraction of the proximal end 58of the shaft 52 is directly transferred to the capsule 50 and causes acorresponding proximal retraction of the capsule 50. In someembodiments, the shaft 52 is further configured to transmit a rotationalforce or movement onto the capsule 50.

The inner shaft assembly 44 can assume a variety of forms appropriatefor supporting a stented prosthetic heart valve within the capsule 50.For example, the inner shaft assembly 44 can include a retention member70, an intermediate tube 72, and a proximal tube 74. In general terms,the retention member 70 is akin to a plunger, and incorporates featuresfor retaining the stented prosthetic heart valve within the capsulesegment 50 as described below. The intermediate tube 72 connects theretention member 70 to the proximal tube 74, with the proximal tube 74,in turn, coupling the inner shaft assembly 44 with the handle 46. Thecomponents 70-74 can combine to define a continuous lumen 76 (referencedgenerally) sized to slidably receive an auxiliary component such as aguide wire (not shown).

The retention member 70 can include a tip 80, a support tube 82, and ahub 84. The tip 80 forms or defines a nose cone having a distallytapering outer surface adapted to promote atraumatic contact with bodilytissue. The tip 80 can be fixed or slidable relative to the support tube82. The support tube 82 extends proximally from the tip 80 and isconfigured to internally support a compressed, stented prosthetic heartvalve generally disposed thereover, and has a length and outer diametercorresponding with dimensional attributes of the prosthetic heart valve.The hub 84 is attached to the support tube 82 opposite the tip 80 (e.g.,adhesive bond), and provides a coupling structure 90 (referencedgenerally) configured to selectively capture a corresponding feature ofthe prosthetic heart valve. The coupling structure 90 can assume variousforms, and is generally located along an intermediate portion of theinner shaft assembly 44. In some embodiments, the coupling structure 90includes one or more fingers sized to be received within correspondingapertures formed by the prosthetic heart valve stent frame (e.g., theprosthetic heart valve stent frame can form wire loops at a proximal endthereof that are received over respective ones of the fingers whencompressed within the capsule 50).

The intermediate tube 72 is formed of a flexible material (e.g., PEEK),and is sized to be slidably received within the delivery sheath assembly40, and in particular the shaft 52. The proximal tube 74 can include aleading portion 92 and a trailing portion 94. The leading portion 92serves as a transition between the intermediate and proximal tubes 72,74, and thus a flexible tubing (e.g., PEEK) having a diameter slightlyless than that of the intermediate tube 72. The trailing portion 94 hasa more rigid construction, configured for robust assembly with thehandle 46. For example, in some constructions, the trailing portion 94is a metal hypotube. Other constructions are also acceptable. Forexample, in other embodiments, the intermediate and proximal tubes 72,74 are integrally formed as a single, homogenous tube or solid shaft.

The handle 46 generally includes a housing 110 and an actuator mechanism112 (referenced generally). The housing 110 maintains the actuatormechanism 112, with the actuator mechanism 112 configured to facilitatesliding movement of the delivery sheath assembly 42 relative to theinner shaft assembly 44, as well as the outer stability tube 48 (whereprovided). The housing 110 can have any shape or size appropriate forconvenient handling by a user. In one simplified construction, theactuator mechanism 112 includes a user interface or actuator 114slidably retained by the housing 110 and coupled to a sheath connectorbody 116. The proximal end 58 of the delivery sheath assembly 42 iscoupled to the sheath connector body 116 (e.g., via an optional mountingboss 118 in some embodiments). The inner shaft assembly 44, and inparticular the proximal tube 74, is slidably received within a passage120 of the sheath connector body 116, and is rigidly coupled to thehousing 110. Sliding of the actuator 114 relative to the housing 110thus causes the delivery sheath assembly 42 to move or slide relative tothe inner shaft assembly 44, for example to effectuate deployment of aprosthesis from the inner shaft assembly 44. A cap 122 can be providedfor attaching the optional outer stability tube 48 to the housing 110(such that the delivery sheath assembly 42 is slidable relative to theouter stability tube 48 with movement of the actuator 114), and can beconfigured to accommodate one or more optional port assemblies 124. Inother embodiments, the outer stability tube 48 can be moveably coupledto the housing 110 in a manner permitting selective sliding of the outerstability tube 48 relative to the delivery sheath assembly 42 (andvice-versa). In yet other embodiments, the outer stability tube 48 canbe eliminated, such that the cap 122 is omitted. Similarly, the actuatormechanism 112 can assume a variety of other forms differing from thoseimplicated by the illustration of FIG. 3.

Where provided, the outer stability tube 48 serves as a stability shaftfor the delivery system 40, and defines a distal end 130, a proximal end132, and a passageway 134 (referenced generally) extending between, andfluidly open at, the ends 130, 132. The passageway 134 is sized tocoaxially receive the delivery sheath assembly 42, and in particular theshaft 52, in a manner permitting sliding of the shaft 52 relative to theouter stability tube 48. Stated otherwise, an inner diameter of theouter stability tube 48 is slightly greater than an outer diameter ofthe shaft 52. As described in greater detail below, the outer stabilitytube 48 has a length selected to extend over a significant (e.g., atleast a majority, and in other embodiments, at least 80%) of a length ofthe shaft 52 in distal extension from the handle 46. Further, the outerstability tube 48 exhibits sufficient radial flexibility to accommodatepassage through a patient's vasculature (e.g., the femoral artery,aortic arch, etc.).

FIGS. 6A and 6B illustrate, in simplified form, assembly of theprosthetic heart valve 20 with the delivery system 40 in defining adevice 150 for repairing a defective heart valve. For ease ofillustration, the valve structure 24 (FIGS. 1A and 1B) is omitted, andonly the stent frame 22 is shown. The prosthetic heart valve 20 isdisposed over the inner shaft assembly 44, with the proximal region(e.g., outflow region) 32 being crimped into engagement with thecoupling structure 90. The capsule 50 is slidably disposed over theprosthetic heart valve 20, compressively retaining the prosthetic heartvalve 20 about the inner shaft assembly 44. In the loaded state of FIG.6B, the distal end 56 of the capsule 50 is positioned immediately distalthe prosthetic heart valve 20, with the distal segment 60 encompassing aportion, but not an entirety, of the prosthetic heart valve 20. Thus,the connection point or intermediate zone 64 of the capsule 50 isradially over the prosthetic heart valve 20. For example, and asdescribed above, the capsule 50 can be configured such that the distalsegment 60 encompasses the distal region (e.g., inflow region) 30 of theprosthetic heart valve 20, whereas the capsule proximal segment 62encompasses the proximal region (e.g., outflow region) 32. In someembodiments, where the distal segment 60 has a larger inner diameterthan that of the proximal segment 62, the prosthetic heart valve 20 canmore easily be loaded within the capsule 50 and crimped relative to theinner shaft assembly 44 with configurations in which the inflow region30 exhibits a greater resistance to radial compression as compared tothe resistance exhibited by the outflow region 32. For example, withconstructions of the prosthetic heart valve 20 in which the valvestructure 24 (FIGS. 1A and 1B) extends along only the inflow region 30such that the outflow region 32 is free of the valve structure material,the inflow region 30 will more overtly resist radially inwardcompression as compared to the outflow region 32; under thesecircumstances, by providing the distal segment 60 with an increasedinner diameter as compared to the proximal segment 62, the prostheticheart valve 20 can more readily be loaded within the capsule 50.

FIGS. 6A and 6B further illustrate the optional outer stability tube 48,including a location of the distal end 130 thereof relative to thecapsule 50 and the prosthetic heart valve 20. In some constructionswhere the outer stability tube 48 is sized to have as great alength/distal extension as possible for supporting the delivery sheathassembly 42, the distal end 130 is located along the shaft 52 (in theloaded state) at a proximal spacing from the distal end 56 by a distancethat is less than twice the axial length of the capsule 50. Statedotherwise, the distal end 130 of the outer stability tube 48 can belocated at a proximal spacing from the connection point 64 approximatelyequal to a length of the distal segment 60 (and any additional deliverysheath body distal the distal segment 60 where included). As a point ofreference, with conventional transcatheter heart valve delivery systemshaving a stiff delivery sheath capsule encompassing an entire length ofthe prosthetic heart valve, the distal end 130 of the outer stabilitytube 48 is proximally spaced from the capsule distal end 56 by adistance sufficient to permit complete withdrawal of the capsule fromover the prosthetic heart valve 20 without any portion of the capsuleentering the outer stability tube 48. FIG. 6C illustrates this prior artarrangement. A comparison of FIGS. 6B and 6C reveals that with thedelivery system 40 of the present disclosure, the distal end 130 of theouter stability tube 48 can extend distally further as compared to priordelivery system arrangements.

The device 150 can be transitioned to a deployed state by withdrawingthe capsule 50 from the prosthetic heart valve 20, as partiallyreflected in FIG. 7. As a point of reference, in the view of FIG. 7, thecapsule 50 has been partially, but not completely, withdrawn from overthe prosthetic heart valve 20. As shown, a distal region 152 of theprosthetic heart valve 20 is exteriorly exposed relative to the capsule50 and self-transitions toward the natural, expanded arrangement, whilea proximal region 154 remains within the capsule 50, engaged with thecoupling structure 90. With further proximal retraction of the capsule50 from the arrangement of FIG. 7 until the distal end 56 of deliverysheath assembly 42/capsule 50 is proximal the prosthetic heart valve 20,the prosthetic heart valve 20 will fully self-expand, and release fromthe delivery system 40. Under circumstances where the clinician desiresto reposition the prosthetic heart valve 20 relative to a desiredimplantation site, the delivery system 40 can alternatively betransitioned from the partially deployed state of FIG. 7 and back to theloaded state of FIG. 6A by distally advancing the capsule 50 back overthe distal region 152 of the prosthetic heart valve 20, therebycompressing the stent frame 22 and recapturing the prosthetic heartvalve 20 relative to the delivery system 40. In this regard, due to thelower area moment of inertia exhibited by the capsule 50 as compared toprior transcatheter, self-expanding heart valve delivery sheaths, thecapsule 50 is unlikely to experience kinking when traversing through thepatient's vasculature, thus enhancing the likelihood that the capsule 50will have sufficient structural integrity to effectuate recapture.

As indicated above, the delivery system 40 is well-suited forpercutaneously delivering the prosthetic heart valve 20 to variousnative valves. One such procedure is schematically reflected in FIG. 8Ain which the device 150 is employed to repair a defective aortic valve160. As shown, the device 150 (in the loaded state) is introduced intothe patient's vasculature 162 (referenced generally) via an introducerdevice 164. The introducer device 164 provides a port or access to afemoral artery 166. From the femoral artery 166, the capsule 50 (thatotherwise compressively retains the prosthetic heart valve 20 (FIG. 6A))is advanced via a retrograde approach through an aortic arch 168 (e.g.,via iliac arteries). In this regard, the aortic arch 168 forms severalsmall radius of curvature bends 170 a, 170 b. In these small radius ofcurvature bends 170 a, 170 b, kinking of the capsule 50 is most likelyto occur. While the increased outer diameter and/or elevated stiffnessof the distal segment 60 may have an increased propensity for bucklingor kinking along the small radius of curvature bends 170 a, 170 b, byshortening a length of the distal segment 60 as compared to conventionaldesigns, the likelihood of kinking when tracking along the aortic arch168 is reduced. While the proximal segment 62 is located adjacent thesecond bend 170 b in the final implantation position of FIG. 8A, thereduced outer diameter and/or area moment of inertia associated with theproximal segment 62 is less likely to experience buckling. Finally, FIG.8A reflects the optional outer stability tube 48 extending along asubstantial length of the delivery sheath assembly 42, with the distalend 130 being fairly proximate the capsule 50. FIG. 8B schematicallyillustrates deployment of the prosthetic heart valve 20 from thedelivery system 40 via proximal retraction of the delivery sheathassembly 42, and in particular the capsule 50. A comparison of FIGS. 8Aand 8B reveals that in the deployed state of FIG. 8B, the proximalsegment 62 of the capsule 50 is retracted within the optional outerstability tube 48.

The devices, systems, and methods of the present disclosure provide amarked improvement over previous designs. By providing the deliverysheath capsule with a shortened segment of increased diameter and/orstiffness, a wall thickness of the capsule is minimized (as compared toconventional stented, self-deploying prosthetic heart valve deliverysystem designs), thus minimizing the potential for kinking that in turnpromotes recaptureability of the prosthetic heart valve. Further, anoverall profile of the delivery system is reduced. The inner diameter ofthe capsule distal segment can be increased for easier prosthetic heartvalve loading and deployment, and a stiffer material can be used for thecapsule distal segment without sacrificing trackability. Finally, withembodiments in which an optional outer stability tube is employed, thedistal end of the stability tube can be distally closer to the distalend of the sheath capsule, and thus can improve deployment accuracyaround the aortic arch.

Although the present disclosure has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges can be made in form and detail without departing from the spiritand scope of the present disclosure.

1. A device for repairing a heart valve of a patient, the devicecomprising: a prosthetic heart valve having a stent frame and a valvestructure attached to the stent frame and forming at least two valveleaflets, the prosthetic heart valve being radially self-expandable froma compressed arrangement to a natural arrangement, the stent framedefining an axial length; and a delivery system comprising: an innershaft assembly including an intermediate portion forming a couplingstructure, a delivery sheath assembly defining a lumen sized to slidablyreceive the inner shaft assembly and including: a shaft, a capsuleextending distally from the shaft and having a distal segment defining afirst outer diameter and a proximal segment defining a second outerdiameter, wherein the first outer diameter is greater than the secondouter diameter, and an axial length of the distal segment is less thanthe axial length of the stent; wherein the device is configured toprovide a loaded state in which the prosthetic heart valve engages thecoupling structure and is compressibly retained within the capsulesegments.
 2. The device of claim 1, wherein a radial stiffness of thedistal segment is greater than a radial stiffness of the proximalsegment.
 3. The device of claim 1, wherein an inner diameter of thedistal segment is greater than an inner diameter of the proximalsegment.
 4. The device of claim 1, wherein an area moment of inertia ofthe distal segment is greater than an area moment of inertia of theproximal segment.
 5. The device of claim 1, wherein a construction ofthe distal segment differs from a construction of the proximal segment.6. The device of claim 5, wherein the distal segment is a metal tubecore, and the proximal segment is a continuation of the shaft.
 7. Thedevice of claim 1, wherein the distal segment terminates at a distal endof the delivery sheath assembly, and further wherein the loaded stateincludes the distal end being immediately distal the prosthetic heartvalve.
 8. The device of claim 1, wherein the prosthetic heart valvedefines an inflow region and an outflow region, and further wherein thedevice is configured such that in the loaded state, the inflow region iscrimped within the distal segment and the outflow region is crimpedwithin the proximal segment.
 9. The device of claim 8, wherein the valvestructure is formed at the inflow region and terminates distal theoutflow region, and further wherein the device is configured such thatin the loaded state, the valve structure is entirely within the distalsegment.
 10. The device of claim 9, wherein the valve structure, asassembled to the stent, has an axial length between opposing terminalends, and further wherein the axial length of the distal segment isgreater than the axial length of the valve structure.
 11. The device ofclaim 1, wherein an intermediate zone is defined at a transition betweenthe distal segment and the proximal segment, and further wherein theloaded state includes the intermediate zone located proximal the valvestructure and over the stent.
 12. The device of claim 1, wherein thedelivery system further includes: an outer stability tube coaxiallyreceived over the delivery sheath and terminating at a distal end;wherein the device is configured such that in the loaded state, thedistal end of the stability tube is proximally spaced from theprosthetic heart valve by a distance that is less than the axial lengthof the capsule.
 13. The device of claim 12, wherein in the loaded state,the distal end of the stability tube is proximally spaced from theprosthetic heart valve by a distance approximating the axial length ofthe distal segment.
 14. The device of claim 12, wherein the device isfurther configured to be transitionable from the loaded state to adeployed state in which the capsule is withdrawn from the prostheticheart valve to permit the prosthetic heart valve to self-expand to thenatural arrangement and release from the delivery system, the deployedstate including at least a portion of the proximal segment being locatedwithin the outer stability tube.
 15. The device of claim 14, wherein theportion of the proximal segment is disposed over the prosthetic heartvalve in the loaded state.
 16. A method of loading a transcatheterdelivery system with a prosthetic heart valve having a stent frame and avalve structure assembled to the stent frame and forming at least twovalve leaflets, the prosthetic heart valve being radiallyself-expandable from a compressed arrangement to a natural arrangement,the method comprising: receiving a delivery system including: an innershaft assembly including an intermediate portion forming a couplingstructure, a delivery sheath assembly defining a lumen sized to slidablyreceive the inner shaft assembly and including a shaft and a capsuleextending distally from the shaft, the capsule including a distalsegment and a proximal segment, wherein an outer diameter of the distalsegment is greater than an outer diameter of the proximal segment;coaxially disposing the prosthetic heart valve over the inner shaftassembly such that a proximal region of the prosthetic heart valve isadjacent the coupling structure; and compressing the prosthetic heartvalve to the compressed arrangement over the inner shaft assembly,including disposing the capsule segments over the prosthetic heart valveand crimping the prosthetic heart valve into engagement with thecoupling structure to achieve a loaded state; wherein the loaded stateincludes the distal segment encompassing a distal region of theprosthetic heart valve and the proximal segment encompassing a proximalregion of the prosthetic heart valve.
 17. The method of claim 16,wherein the distal region of the prosthetic heart valve is an inflowregion and the proximal region is an outflow region.
 18. The method ofclaim 16, wherein the loaded state includes the distal segmentencompassing an entirety of the valve structure and less than anentirety of the stent frame.
 19. The method of claim 16, wherein aradial stiffness of the distal segment is greater than a radialstiffness of the proximal segment.
 20. The method of claim 16, whereinan inner diameter of the distal segment is greater than an innerdiameter of the proximal segment.
 21. The method of claim 16, wherein anarea moment of inertia of the distal segment is greater than an areamoment of inertia of the proximal segment.
 22. The method of claim 16,wherein a construction of the distal segment differs from a constructionof the proximal segment.
 23. A method of repairing a defective heartvalve of a patient, the method comprising: receiving a delivery systemloaded with a radially self-expandable prosthetic heart valve having astent frame to which a valve structure is attached, the delivery systemincluding an inner shaft assembly coaxially received within a deliverysheath assembly having a capsule forming a distal segment and a proximalsegment, the distal segment having an outer diameter greater than anouter diameter of the proximal segment, wherein the distal segment isdisposed over and compressively retains a distal region of theprosthetic heart valve and the proximal segment is disposed over andcompressively retains a proximal region of the prosthetic heart valvesuch that the prosthetic heart valve is in a compressed arrangementwithin the capsule; inserting the prosthetic heart valve into a bodilylumen while the prosthetic heart valve is constrained within thecapsule; manipulating the delivery system to guide the prosthetic heartvalve through the patient's vasculature and into the defective heartvalve; and withdrawing the capsule from the prosthetic heart valve topermit the prosthetic heart valve to self-expand and release from thedelivery system and into engagement with the native heart valve.
 24. Themethod of claim 23, wherein manipulating the delivery system to guidethe prosthetic heart valve through the patient's vasculature includestracking the prosthetic heart valve around the patient's aortic arch.25. The method of claim 24, wherein tracking the prosthetic heart valvearound the patient's aortic arch includes the capsule not experiencingkinking when tracking across the patient's aortic arch.
 26. The methodof claim 23, wherein prior to the step of withdrawing the capsule topermit the prosthetic heart valve to release from the delivery system,the method further comprising: partially retracting the capsule from theprosthetic heart valve such that an exposed region of the prostheticheart valve self-expands while a trailing region of the prosthetic heartvalve remains constrained within the capsule; and distally advancing thecapsule over the exposed region to recapture the prosthetic heart valverelative to the delivery system.